Synchronization with a bias supply in a plasma processing system

ABSTRACT

Plasma processing systems and methods are disclosed. The method includes generating and sustaining a plasma in a plasma chamber and producing a surface potential on a surface of a workpiece in the plasma chamber by applying, with a bias supply, an output waveform to a bias electrode within the plasma chamber where the output waveform has a repetition period, T. A waveform dataset is produced to represent the output waveform of the bias supply during the repetition period, T, and the waveform dataset is sent to one or more other pieces of equipment connected to the plasma chamber. A synchronization pulse with a synchronization-pulse-repetition-period is sent to the one or more other pieces of equipment connected to the plasma chamber to enable synchronization among the one or more other pieces of equipment.

CLAIM OF PRIORITY UNDER 35 U.S.C. § 120

The present Application for Patent is a Continuation of patentapplication Ser. No. 16/194,125 entitled “APPLICATION OF MODULATINGSUPPLIES IN A PLASMA PROCESSING SYSTEM” filed Nov. 16, 2018, pending,which claims priority to Provisional Application No. 62/588,255 entitled“IMPROVED APPLICATION OF AN EV SOURCE IN PLASMA PROCESSING EQUIPMENT”filed Nov. 17, 2017, and assigned to the assignee hereof and herebyexpressly incorporated by reference herein.

BACKGROUND Field

The present disclosure relates generally to plasma processing. Inparticular, but not by way of limitation, the present disclosure relatesto interoperation of equipment coupled to a plasma processing system.

Background

Plasma processing systems for etching and deposition have been utilizedfor decades, but advancements in processing techniques and equipmenttechnologies continue to create increasingly more complex systems. Atthe same time, the decreasing dimensions of structures created withworkpieces requires increasingly precise control and interoperation ofplasma processing equipment. Current control methodologies andassociated systems are not capable of addressing several issues that areassociated with the complex systems of today and tomorrow; thus, thereis a need for new and improved control over disparate, yetinterdependent, plasma processing equipment.

SUMMARY

According to an aspect, a method includes generating and sustaining aplasma in a plasma chamber and producing a surface potential on asurface of a workpiece in a plasma chamber by applying, with a biassupply, an output waveform to a bias electrode within the plasma chamberwhere the output waveform has a repetition period, T. A waveform datasetis produced to represent the output waveform of the bias supply duringthe repetition period, T, and the waveform dataset is sent to one ormore other pieces of equipment connected to the plasma chamber. Asynchronization pulse with a synchronization-pulse-repetition-period issent to the one or more other pieces of equipment connected to theplasma chamber to enable synchronization among the one or more otherpieces of equipment.

Another aspect may be characterized as a plasma processing system thatincludes a bias supply to apply an output waveform having a repetitionperiod, T, and a synchronization module configured to send asynchronization-signal-repetition-period that is an integer multiple ofT to at least one other piece of equipment connected to the plasmasystem. A waveform communication module configured to communicatecharacteristics of the output waveform generated by the bias supply tothe at least one other piece of equipment connected to the plasmasystem.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an embodiment of a plasma processing system designed toachieve control over plasma properties.

FIG. 2 depicts another embodiment of plasma processing system designedto achieve control over plasma properties using a remote plasma sourcerather than a source generator or source generators.

FIG. 3 depicts yet another embodiment of a plasma processing systemdesigned to achieve control over plasma properties using a remote plasmasource and an integrated bias power delivery system.

FIG. 4 depicts a plasma processing system that includes a bias supply.

FIG. 5 depicts another implementation of a plasma processing systemincorporating multiple bias supplies.

FIG. 6 is a diagram depicting aspects of an exemplary bias supply.

FIG. 7 includes a graph of a voltage waveform output from a bias supply;a graph of a corresponding sheath voltage; and a correspondingswitch-timing diagram.

FIG. 8A depicts an implementation using two voltage sources to providevoltages to the bias supply depicted in FIG. 11;

FIG. 8B depicts another implementation using two voltage sources toprovide voltages to the bias supply depicted in FIG. 11.

FIG. 8C depicts yet another implementation using two voltage sources toprovide voltages to the bias supply depicted in FIG. 11.

FIG. 9A depicts an implementation using three voltage sources to providevoltages to the bias supply depicted in FIG. 11.

FIG. 9B depicts another implementation using three voltage sources toprovide voltages to the bias supply depicted in FIG. 11.

FIG. 9C depicts yet another implementation using three voltage sourcesto provide voltages to the bias supply depicted in FIG. 11.

FIG. 10 is a block diagram depicting a synchronization controlcomponent.

FIG. 11 is a method that may be traversed using the synchronizationcontrol component.

FIG. 12 depicts aspects of synchronizing a modulating supply with otherequipment connected to plasma processing system.

FIG. 13 is a flowchart depicting an exemplary method that may beexecuted from a master device;

FIG. 14 is a flowchart depicting an exemplary method that may beexecuted by a slave device;

FIG. 15 is a block diagram depicting components that may be utilized toimplement control aspects disclosed herein.

DETAILED DESCRIPTION

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

Preliminary note: the flowcharts and block diagrams in the followingFigures illustrate the architecture, functionality, and operation ofpossible implementations of systems, methods and computer programproducts according to various embodiments of the present invention. Inthis regard, some blocks in these flowcharts or block diagrams mayrepresent a module, segment, or portion of code, which comprises one ormore executable instructions for implementing the specified logicalfunction(s). It should also be noted that, in some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustrations, and combinations ofblocks in the block diagrams and/or flowchart illustrations, can beimplemented by special purpose hardware-based systems that perform thespecified functions or acts, or combinations of special purpose hardwareand computer instructions.

While the following disclosure generally refers to wafer plasmaprocessing, implementations can include any substrate processing withina plasma chamber. In some instances, objects other than a substrate canbe processed using the systems, methods, and apparatus herein disclosed.In other words, this disclosure applies to plasma processing of anyobject within a sub-atmospheric plasma processing chamber to effect asurface change, subsurface change, deposition or removal by physical orchemical means.

This disclosure may utilize plasma processing and substrate biasingtechniques as disclosed in U.S. Pat. No. 9,287,092, U.S. Pat. No.9,287,086, U.S. Pat. No. 9,435,029, U.S. Pat. No. 9,309,594, U.S. Pat.No. 9,767,988, U.S. Pat. No. 9,362,089, U.S. Pat. No. 9,105,447, U.S.Pat. No. 9,685,297, U.S. Pat. No. 9,210,790. The entirety of theseapplications is incorporated herein by reference. But it should berecognized that the reference in this specification to any priorpublication (or information derived from it), or to any matter which isknown, is not an acknowledgment or admission or any form of suggestionthat the prior publication (or information derived from it) or knownmatter is conventional, routine, or forms part of the common generalknowledge in the field of endeavor to which this specification relates.

For the purposes of this disclosure, source generators are those whoseenergy is primarily directed to generating and sustaining the plasma,while “bias supplies” are those whose energy is primarily directed togenerating a surface potential for attracting ions and electrons fromthe plasma.

FIG. 1 shows an embodiment of a plasma processing system with manypieces of equipment coupled directly and indirectly to plasma chamber101, which contains a plasma 102. The equipment includes vacuum handlingand gas delivery equipment 106, bias generators 108, a bias matchingnetwork 110, bias measurement and diagnostics 111, source generators112, a source matching network 113, source measurement and diagnostics114, measurement and diagnostics 115, and a system controller 116. Theembodiment in FIG. 1, and other embodiments described herein, areexemplary of the complexity of plasma processing systems, and thedepiction of plasma systems herein helps to convey the interrelations ofthe equipment coupled to the plasma chamber 101.

An example of the interrelations of the plasma processing equipment isthe effect that modulating supplies (e.g., source generators 112, biasgenerators 108, and other modulating supplies discussed further herein)have on plasma properties (and control of the same). More specifically,modulating supplies can cause strong modulation of plasma propertiessuch as the impedance presented by the plasma 102 to equipment of theplasma processing system 100. Plasma modulation can also cause aliasingof measurements of plasma properties. Additional details about theeffects of modulation of plasma properties are discussed further herein.

Shown in FIG. 1 is a plasma processing system 100 (e.g., deposition oretch system) containing a plasma chamber 101 within which a workpiece(e.g., a wafer) 103 is contained. A number of bias electrodes 104 areconnected through the bias measurement and diagnostic system 111 to thebias match network 110 to which a number of bias generators 108 areconnected. The bias electrodes 104 may be built into an electrostaticchuck to hold the workpiece 103 in place. This may involve integrationof a high voltage DC power supply 107 into the system. In manyapplications, a single bias electrode 104 is used, but utilization ofmany bias electrodes 104 may be used to achieve a desired spatialcontrol.

The bias generators 108 depicted in FIG. 1 may be lower frequency (e.g.,400 kHz to 13.56 MHz) RF generators that apply a sinusoidal waveform.Also shown is a set of source electrodes 105 connected to a number ofsource generators 112 through the source measurement and diagnosticssystem 114 and source matching network 113. In many applications, powerfrom a single source generator 112 is connected to one or multiplesource electrodes 105. The source generators 112 may be higher frequencyRF generators (e.g. 13.56 MHz to 120 MHz). Vacuum maintenance, gasdelivery and wafer handling equipment 106 may be implemented to completethe system and optionally additional measurement and diagnosticequipment 115 may be present (e.g. optical spectroscopy equipment).

The system controller 116 in the embodiment of FIG. 1 controls theentire system through a system control bus 117. The system control bus117 can also be used to collect information from equipment of the plasmaprocessing system. In addition to the system control bus 117, there maybe dedicated inter-system communication 118 which can be used, forexample, to control the source matching network 113 from a sourcegenerator 112 or exchange information between subsystems withoutinvolving the system control bus 117. There may also be a near-real-timecommunication link 119 between subsystems. This may take the form of areference oscillator to phase lock different generators on the system,to provide waveform synchronization signals, arc detection signals, etc.Although a single source generator 112 is common, it is also common tohave multiple source generators 112 and multiple bias generators 108 inorder to achieve a desired plasma density and desired control over thedistribution of ion energies. One or more of the source generators 112and/or bias generators 108 can modulate the plasma properties and beconsidered as a modulating supply.

FIG. 2 shows an embodiment of a plasma processing system 200 where thesource generators 112 are replaced by a remote plasma source 205. Asthose of ordinary skill in the art will appreciate, the remote plasmasource 205 may include an excitation source (e.g., an RF generator) anda plasma-generation chamber configured and disposed to produce a plasmathat is provided to the plasma chamber 101. Although the remote plasmasource 205 is outside of the plasma chamber 101, the remote plasmasource 205 may be coupled to the plasma chamber 101 to form a contiguousvolume with the plasma chamber 101. Although unlikely in manyembodiments, in some embodiments, the remote plasma source 205 maymodulate plasma properties of the plasma 102 in the plasma chamber 101.And if the remote plasma source 205 does modulate the plasma propertiesof the plasma 102, the remote plasma source 205 and/or one or more ofthe bias generators 108 can be considered as a modulating supply.

FIG. 3 shows another embodiment of a plasma processing system wheremultiple bias generators are replaced by an integrated bias powerdelivery system 308. Such integration can reduce system complexity andreduce duplication by, for example, using common DC power supplies forthe RF generators, a common controller, auxiliary power supplies,measurement systems etc., but the output to the plasma chamber 101 isstill a combination of a single or multiple RF frequencies and/or a DCsignal. Many other variations exist such as, for example, using a sourcegenerator and integrated bias power delivery system or using integratedsource and bias power delivery systems etc.

Referring next to FIG. 4, shown is yet another embodiment of a plasmaprocessing system that utilizes a bias supply 408 (instead of biasgenerators 108) for an even tighter control over the distribution of ionenergies. As shown, the bias supply 408 may apply a periodic waveform toseveral different electrodes 104, or alternatively, a separate biassupply 408 may be coupled to each electrode 104 (not shown in FIG. 4).As shown in FIG. 5, it is contemplated that multiple bias supplies 508may be utilized in connection with multiple generators 109. It should berecognized that the embodiments described with reference to FIGS. 1-5are not mutually exclusive and that various combinations of the depictedequipment may be employed.

Referring next to FIG. 6, shown is a general representation of anexemplary bias supply 608 that may be used to realize the bias supplies408, 508. As shown, the bias supply 608 utilizes three voltages V1, V2,and V3. Because the output, Vout, is capacitively coupled throughCchuck, it is generally not necessary to control the DC level of Voutand the three voltages can be reduced to two by choosing one of V1, V2or V3 to be ground (0V). A separate chucking supply 107 may be used soit is not necessary to control the DC level of Vout. If a separatechucking supply is not used, all three voltages can be controlled tocontrol the DC level of Vout. Although not shown for clarity, the twoswitches S1, and S2 may be controlled by a switch controller viaelectrical or optical connection to enable the switch controller to openand close the switches, S1, S2, as disclosed below. The depictedswitches S1, S2 may be realized by single pole, single throw switches,and as a non-limiting example, the switches S1, S2 may be realized bysilicon carbide metal-oxide semiconductor field-effect transistors (SiCMOSFETs).

In this implementation, the voltages V1, V2, and V3 may be DC-sourcedvoltages. As shown, the first switch, S1, is disposed to switchablyconnect the first voltage, V1, to the output, Vout, through andinductive element and the second switch, S2, is disposed to switchablycouple the second voltage, V2, to the output, Vout, through an inductiveelement. In this implementation the two switches connect to a commonnode, 670, and a common inductive element, L1, is disposed between thecommon node and an output node, Vout. Other arrangements of theinductive elements are possible. For example, there may be two separateinductive elements with one inductive element connecting S1 to Vout andanother connecting S2 to Vout. In another example one inductive elementmay connect S1 to S2 and another inductive element may connect either S1or S2 to Vout.

While referring to FIG. 6, simultaneous reference is made to FIG. 7,which depicts: 1) the voltage waveform of the bias supply 608 that isoutput at Vout; 2) a corresponding sheath voltage; and 3) correspondingswitch positions of switches S1 and S2. In operation, the first switch,S1, is closed momentarily to increase, along a first portion 760 of thevoltage waveform (between voltage V0 and Va) a level of the voltage atthe output node, Vout, to a first voltage level, Va. The level Va ismaintained along a second portion 762 of the waveform. The secondswitch, S2, is then closed momentarily to decrease, along a thirdportion 764 of the waveform, the level of the voltage waveform at theoutput node, Vout, to a second voltage level, Vb. Note that S1 and S2are open except for short periods of time. As shown, the negativevoltage swing along the third portion 764 affects the sheath voltage(Vsheath); thus, a magnitude of Va-Vb may be controlled to affect thesheath voltage.

In this embodiment the third voltage, V3, is applied to the output node,Vout, through a second inductive element L2 to further decrease a levelof the voltage at the output node along a fourth portion 766 of thevoltage waveform. As shown in FIG. 7, the negative voltage ramp alongthe fourth portion 766 may be established to maintain the sheath voltageby compensating for ions that impact the substrate.

Thus, S1 momentarily connects and then disconnects the first voltage,V1, to the output, Vout, through the first inductive element L1, andafter a period of time, S2 connects and then disconnects the secondvoltage (e.g., ground) to the output, Vout, through the first inductiveelement L1. The third voltage, V3, is coupled to the output, Vout,through a second inductive element L2. In this implementation, the firstvoltage, V1, may be higher than the third voltage V3, and the momentaryconnection and disconnection of the first voltage, V1, to the outputVout causes the voltage of the output, Vout, to increase along the firstportion 760 of the voltage waveform to a first voltage level, Va, andthe first voltage level, Va, is sustained along the second portion ofthe waveform 762. The first voltage level Va may be above the firstvoltage, V1, and the second voltage, V2, (e.g., ground) may be less thanthe first voltage level, Va. The momentary connecting and thendisconnecting of the second voltage, V2, causes the voltage of theoutput, Vout, to decrease at the third portion 764 to the second voltagelevel Vb that is below the second voltage, V2 (e.g., ground).

As an example, V1 may be −2000 VDC; V2 may be ground; V3 may be −5000VDC; V0 may be −7000 VDC; Vb may be −3000 VDC; and Va may be 3000 VDC.But these voltages are merely exemplary to provide context to relativemagnitude and polarities of the voltages described with reference toFIGS. 6 and 7.

Referring next to FIGS. 8A-8C shown are possible arrangements of two DCvoltage sources to provide the voltages V1, V2, and V3 depicted in FIG.6. In FIG. 8A, V2 is grounded and forms a common node between the two DCvoltage sources. In FIG. 8B, V1 is grounded and V2 forms a common nodebetween the DC voltage sources. And in FIG. 8C, V1 is grounded and formsa common node between each of the two DC voltage sources.

In some embodiments, as shown in FIGS. 9A, 9B, and 9C, three DC voltagesources may be utilized to apply the three voltages V1, V2, and V3. Asshown in FIG. 9A, each of the three DC voltage sources may be coupled toground, and each of the three DC voltage sources provides acorresponding one of V1, V2, V3. In FIG. 9B one of the DC voltagessources is grounded and the three DC voltage sources are arranged inseries. In FIG. 9C, one of DC voltages sources is disposed betweenground and V2, and each of the DC voltage sources is coupled to V2.

The bias supply 608 depicted in FIG. 6 is merely an example of a biassupply 608 that may produce an output at Vout as shown in FIG. 7. Othervariations are shown and described the incorporated-by-reference patentsreferred to earlier herein. Also disclosed in theincorporated-by-reference patents are different modulation schemes thatmay be applied to the basic source waveform (at Vout) to achieve adesired distribution of ion energies and to control average powerapplied to the plasma chamber by the bias supply.

One modulation scheme includes modulating the third portion 764 of thevoltage waveform to effectuate desired ion energies of ions impingingupon the workpiece 103 in the plasma chamber 101. As an example, thebias supply 408, 508, 608 may alternate a magnitude of the third portion764 of the voltage waveform between two or more levels to effectuate analternating surface potential of the workpiece 103 in the plasma betweentwo or more distinct levels. As another example, a slope of the fourthportion 766 of the voltage waveform may be adjusted to change a level ofcurrent that is provided to an electrode 104 (to compensate for ioncurrent that impinges upon the workpiece 103) to achieve a desiredspread of ion energies (e.g., around a center ion energy). Successfuluse of bias supplies 408, 508, 608 as a bias generator in many plasmaprocessing systems requires careful system design.

System Synchronization and Communication

Modulating supplies such as the source generators 112, bias generators108, remote plasma sources 205, and bias supplies 408, 508, 608 cancause strong modulation of plasma properties. Examples of plasmaproperties, without limitation, include an impedance presented by theplasma, plasma density, sheath capacitance, and a surface potential ofthe workpiece 103 in the plasma 102. As discussed above, the modulationof the voltage and/or current applied by the bias supplies 408, 508, 608is one potential cause of modulating plasma properties.

Source generators 112 may also modulate plasma properties by modulatingelectromagnetic fields impacting the plasma 102. In particular, sourcegenerators may pulse the power (e.g., RF power) that is applied by asource generator 112. Moreover, a magnitude of voltage of the powerapplied by a source generator 112 may be changed. The addition of one ormore additional source generators 112 adds additional complexity. And itis also contemplated that one or more bias supplies 408, 508, 608 maymodulate the voltage (Vout shown in FIG. 6), and hence sheath voltage,while a source generator 112 is applying pulsed power. Thus, controlover plasma properties (e.g., plasma density and ion energy) ischallenging, and spatial control over the plasma properties isespecially challenging.

As discussed above, a remote plasma source 205 may replace, or augment,a source generator 112. But remote plasma sources 205 may also bemodulating supplies that are configured to modulate plasma properties bymodulating properties of gases in the plasma chamber 101.

In addition to control challenges, one modulating supply may affect(e.g., in an adverse manner) operation of another modulating supply. Asa specific, non-limiting, example, the bias supplies 408, 508, 608 mayimpart power at a level that results in plasma modulation, which inturn, cause undesirable changes in the load impedance presented to asource generator 112. In addition, strong plasma modulation can alsocause aliasing of measurements of plasma properties. The aliasing mayprevent accurate measurements of forward and reflected power; thus,preventing an operator from detecting damaging power levels and/orprevent proper control over at least one of the source matching network113 or the bias matching network 110.

Synchronization of equipment connected to the plasma system may mitigatethe adverse effects of plasma modulation (e.g., damaging power andaliasing), and as a consequence, synchronization is highly desired. Butthe complex, time varying, aspects of plasma modulation (e.g., resultingfrom potentially many modulating supplies) can make synchronizationdifficult.

Referring to FIG. 10, shown is a synchronization controller 1016 that isconfigured to synchronize constituent equipment of a plasma processingsystem that may include modulating supplies and other equipment thatdoes not modulate the plasma 102. As shown, the synchronizationcontroller 1016 includes a user interface 1050, awaveform-characterization module 1052, a waveform-repetition module1054, a waveform-communication module 1056, and a synchronization module1058.

The depicted components of the synchronization controller 1016 may berealized by hardware, firmware, software and hardware or combinationsthereof. The functional components of the synchronization controller1016 may be distributed about the plasma processing system andduplicated in equipment that is connected to the plasma processingsystem. And as discussed further herein, the synchronization controller1016 may be implemented as a master device or slave device.

The user interface 1050 enables an operator to interact with the plasmaprocessing system so that the operator may control aspects of thesynchronization and the operator may receive information aboutconditions of the equipment and the plasma chamber 101. The userinterface 1050 may be realized, for example, by one or more of a touchscreen, pointing device (e.g., mouse), display, and keyboard.

The waveform-characterization module 1052 is generally configured togenerate a waveform dataset that characterizes a waveform (e.g., awaveform of a modulation of the plasma or a waveform output (or desiredto be output) by equipment) of the plasma processing system. Thewaveform-repetition module 1054 is configured to determine a repetitionperiod, T, for a piece of equipment connected to the plasma system, andthe waveform-communication module 1056 is configured to communicate thewaveform dataset to at least one of the piece of equipment or anotherpiece of equipment connected to the plasma processing system. Thesynchronization module 1058 is configured to send a synchronizationpulse with a synchronization-pulse-repetition-period (which is aninteger multiple of T) to one or more pieces of equipment connected tothe plasma system.

While referring to FIG. 10, simultaneous reference is made to FIG. 11,which is a flowchart depicting a method that may be traversed inconnection with a plasma processing system and the synchronizationcontroller 1016. As shown, plasma properties are modulated with amodulating supply where the modulation has a repetition period, T (Block1100). It should be recognized that in many embodiments T is therepetition period of the plasma modulation—not a cycle period of themodulating supply. As a consequence, the modulating supply may have anoutput with a repetition period that is different than the modulation ofthe plasma properties. For example, the modulating supply may have arepetition period of 200 microseconds and another modulating supply mayhave a repetition period of 500 microseconds resulting in the plasma 102being modulated with a 1 millisecond repetition period, T. In someembodiments, T is a shortest length of time for which waveforms of allpieces of equipment that modulate the plasma properties of the plasmaprocessing system is periodic with period, T.

As shown in FIG. 11, the waveform characterization module 1052 maycharacterize a waveform with a repetition period, T, containing at leastone of information about the modulation of the plasma or a desiredwaveform of a piece of equipment connected to the plasma processingsystem to produce a waveform dataset (Block 1102).

Referring briefly to FIG. 12, shown are: an exemplary output waveform1201 of the bias supply 408, 508, 608; a corresponding waveform 1203 isa calculated effective voltage at the surface of the workpiece 103; acorresponding synchronization signal 1204; and information about thewaveform in the form of a waveform dataset 1205. In FIG. 12, the outputwaveform 1201 is the actual output of the bias supply 408, 508, 608 (atVout) with a fundamental period, T, 1202. The waveform 1203 is acalculated effective voltage at the surface of the workpiece 103 (e.g.,a sheath voltage that is the voltage of the workpiece 103 relative tothe plasma 102). Also shown is a synchronization pulse 1204 (alsoreferred to as a synchronization signal 1204) with asynchronization-signal-repetition-period that is an integer multiple ofT. And the waveform dataset 1205 that includes information about thewaveform 1203; thus, a characterized waveform (represented in FIG. 12)is the waveform 1203. It should be recognized that the waveform 1203represents an alternating surface potential of the workpiece between twoor more distinct levels (e.g., −500V and −1000V), but this is only anexample and is not required. Alternatively, the characterized waveformmay be an output waveform generated by a modulating supply, which inFIG. 12 is the output waveform 1201 of the bias supply 408, 508, 608. Inyet another implementation, the characteristics of the waveform with arepetition period T include characteristics of the plasma propertiessuch as plasma density, sheath capacitance, sheath potential, etc.

Referring again to FIG. 11, the waveform dataset 1205 is sent by thewaveform-communication module 1056 to the at least one piece ofequipment connected to the plasma system (Block 1104), and thesynchronization module 1058 sends the synchronization signal 1204 with asynchronization-signal-repetition-period (which is an integer multipleof T) to at least one piece of equipment connected to the plasma system(Block 1106). This method enables synchronization of pieces of equipmentconnected to the plasma processing system where the characterizedwaveform contains at least one of information about the modulation ofthe plasma or information about a desired waveform of a piece ofequipment connected to the plasma processing system. It should berecognized that the waveform dataset may be communicated to areceiving-piece of equipment to control the receiving-piece of equipment(e.g., by directing the receiving-piece of equipment to provide adesired waveform). Or the waveform dataset may be informational (e.g.,to provide information about the modulation of the plasma or to provideinformation about an output of a modulating supply).

Although FIG. 12 depicts a specific example of a modulating supply thatapplies power with a waveform that enables control over ion energy in aregion proximate to an electrode 104, the waveform characterization(Block 1106) is generally applicable to other waveforms that mayrepresent aspects of plasma-related modulation (e.g., plasma density,plasma impedance, ion flux, etc.) or aspects of power applied by otherequipment. For example, equipment coupled to the plasma processingsystem may include RF and DC generators, and in some implementations,the generator(s) are able to absorb power from the plasma processingsystem. It is also contemplated that in some embodiments one or moregenerators are a load that can only absorb power from the plasmaprocessing system. Generators that are able to absorb power are usefulfor controlling spatial properties of an electromagnetic field in aplasma chamber by, e.g., avoiding standing waves in the chamber.

One or more of the source generators 112 may synchronize a property ofthe output of the source generator(s) 112 with the characterizedwaveform (that has the repetition period T). The property of the outputof the source generator(s) 112 may be at least one of voltage, current,power, frequency, or generator source impedance. And the output of thesource generator(s) 112, for example, may include (within one repetitionperiod) pulsed power followed by continuous wave power. And the waveformdataset may include a time series of values indicating one or moreaspects of power (e.g., voltage, current, phase, etc.) for therepetition period. The source generator 112 may synchronize pulsing witha particular waveform applied by the bias supply 408, 508, 608 that may,for example, modulate a magnitude of the negative voltage swing (thethird portion 764) in a different manner while the source generator 112is pulsing as compared to when the source generator 112 is operating ina continuous-wave mode of operation. This use case is only an example,and various other types of processing steps may prompt synchronizationamong pieces of plasma processing equipment.

In addition, the source generator 112 may advance or delay changes in aproperty of the output of the source generator 112 with respect tochanges in the characterized waveform with a repetition period T. Asdiscussed above, the characterized waveform in some implementations maycharacterize the modulation of the plasma properties. The characterizedwaveform may also characterize a waveform of the source generator 112 oranother modulating supply (depending upon how the source generator 112is configured to operate).

The equipment coupled to the plasma processing system (and synchronizedas disclosed herein) is certainly not limited to modulating supplies.For example, the at least one piece of equipment that the dataset issent to (Block 1104) may include equipment that is configured to measureproperties of the plasma processing system. For example, themeasurements may include at least one of a measurement of plasmaproperties, properties of power delivered to the plasma system, orproperties of gas delivered to the plasma system. By way of furtherexample, the equipment that is configured to measure properties mayinclude one or more of the source measurement and diagnostics system 114and the bias measurement and diagnostics system 111. Those of ordinaryskill in the art recognize that the source measurement and diagnosticssystem 114 and the bias measurement and diagnostics system 111 mayinclude one or more sensors (e.g., directional couplers and/or VIsensors) in connection with hardware to sample and analyze properties ofpower delivered to the plasma system (which may be used to measureplasma impedance as a plasma property). In the context of a plasmaprocessing system utilizing the remote plasma source 205, properties ofthe gas delivered to the plasma processing system may be measured (e.g.,utilizing optical or other measurement techniques). As discussed herein,plasma modulation can cause aliasing of measurements of plasmaproperties, so synchronizing measurements to within time windows toavoid misleading transient values (or during time windows wheremodulation is at a local minima) is beneficial.

Other equipment that may be synchronized includes matching networks. Forexample, the impedance matching network may synchronize measurementsindicative of impedance with the characterized waveform. Bysynchronizing the measurements with time windows where measurements arenot misleading (e.g., when there not large changes in power levelsapplied to the plasma), matching may be improved. Examples of impedancematching networks include the source matching network 113 and the biasmatching network 110.

The waveform dataset 1205 may be sent (Block 1104) via digitalcommunication link to one or more of the pieces of equipment coupled tothe plasma processing system. The communication link may include thesystem control bus 117, which may be realized by known digital links(for example, without limitation, ethernet). In many implementations,the waveform dataset 1205 may be communicated once, and then thesynchronization pulse prompts each piece of equipment to operate inresponse to the waveform dataset in a repeating manner.

The synchronization signal may be sent (Block 1106) via thenear-real-time communication link 119 to equipment coupled to the plasmaprocessing system. As an example, the near-real-time link may be ananalog communication link to provide a single analog output with anidentifiable fundamental pulse (also referred to as a “tick”)), and ifrequired, update pulses (also referred to as “update-ticks”) are sent inbetween the fundamental pulses. In addition, the synchronization signalmay include an indication of a start of the synchronization signalrepetition period as well as at least one indication that a period oftime since the start of the synchronization signal repetition period haselapsed.

The start of the synchronization signal repetition period may beindicated by a pulse of a first duration and the indication that aperiod of time since the start of the synchronization signal repetitionperiod has elapsed may be indicated by a pulse of a second duration thatis different from the first duration. For example, the first durationmay be longer than the second duration or vice versa.

In some implementations, the synchronization signal includes anindication of the start of the synchronization signal repetition periodwhere the start of the synchronization signal repetition period isfurther modified at least once to indicate a time of day or to indicatethat a new waveform is taking effect.

Referring to FIGS. 13 and 14 shown are flowcharts depicting activitiescarried out at a master piece of equipment and activities carried out ata slave piece of equipment, respectively. As shown in FIG. 13, at amaster piece of equipment, information on desired waveforms forequipment connected to the plasma processing equipment is obtained(Block 1300), and a fundamental repetition period is determined (Block1302). A determination is also made to establish whether anyintermediate synchronization pulses are necessary to maintain accuracy(Block 1304). Waveform datasets are generated (Block 1306) and thencommunicated to equipment connected to the plasma processing system(Block 1308). In addition, synchronization pulses are provided toequipment connected to the plasma processing system (Block 1310). Asshown, intermediate synchronization pulses are provided to equipment ifnecessary (Block 1312). And information about whether a sequence shouldchange is also obtained (Block 1314), and if the sequence should change(Block 1316), then the activities described above with reference toBlocks 1300 to 1314 are performed again.

As shown in FIG. 14, at a slave piece of equipment, a waveform datasetis received (Block 1400), and the slave then waits for astart-of-sequence pulse to be received (Block 1402) before setting atime to zero (Block 1404). The slave equipment then waits for a pulse tobe received (Block 1406) and determines whether or not the pulse was astart-of-sequence pulse (Block 1408), and if so, a time is set to zero(Block 1410). If the received pulse is not a start-of-sequence pulse(Block 1408), then the time is synchronized to a timing of the receivedpulse (Block 1412). As shown, if a new waveform dataset is received(Block 1414), then a new-waveform-dataset-received-flag is set (Block1416). If the new-waveform-dataset-received-flag is set (Block 1418) andthe received pulse is modified to indicate a change to a new dataset(Block 1420), then the new-waveform-dataset-received-flag is cleared andthe new waveform dataset is utilized (Block 1422).

By utilizing precision oscillators, synchronization can be maintainedwith good precision. For example, using 50 ppm oscillators in allequipment, a change in a waveform can be predicted with better than 50ns accuracy for a fundamental pulse repetition rate as low as 10 kHz.For longer pulse repetition periods one can add additionalsynchronization pulses every 100 μs to maintain synchronization within50 ns accuracy.

Synchronization between a source generator 112 and bias supply 408, 508,608 may entail lowering voltage or cutting off voltage at the end of agiven bias supply pulse. For example, it may be desirable to avoidending an RF pulse in the midst of a bias supply pulse. Alternatively,pulsing or periodic reductions in voltage, may start and end at the samepoint/phase in the bias supply pulse, but for different pulses. In otherwords, it may be desirable to set the pulse on length equal to aninteger number of bias supply pulses, whether or not the envelope pulseis in phase with a start or end to an individual bias supply pulse.

The previously described embodiments provide novel and nonobvioussystems and methods to create laminate films, among other use cases.Examples such as diamond like carbon, which when deposited with plasmaprocessing has very high stresses that can result in peeling of thefilm, can now be processed to incorporate low stress graphite oramorphous carbon layers so that the overall film still exhibits diamondlike carbon properties but at lower stresses. In some films, it may bedesirable to deposit the film in one period followed by a period wherethe plasma chemistry is modified by pulsing control and a high bias isapplied to densify the film. Aspects described herein enable productionof nano-level “Bragg” structures consisting of alternative layers withdifferent optical properties produced by combining pulsing and biasvoltage control in each respective period as illustrated earlier. Saidanother way, a first chemistry can be achieved for a first period oftime to deposit a first layer, then a second chemistry can be achievedfor a second period of time to deposit a second layer. This can berepeated numerous times to achieve a “Bragg” structure. The differentchemistries can be achieved by variations in one or more of: biasvoltage; duty cycle of two or more bias voltages; alterations in thetiming of bias voltage, source pulsing; duty cycle of source pulsing;source voltage; and source voltage and pulsing in combination.

The methods described in connection with the embodiments disclosedherein may be embodied directly in hardware, in processor-executablecode encoded in a non-transitory tangible processor readable storagemedium, or in a combination of the two. Referring to FIG. 15 forexample, shown is a block diagram depicting physical components that maybe utilized to realize synchronization logic that may be implemented inequipment coupled to the plasma processing systems disclosed herein. Asshown, in this embodiment a display portion 1512 and nonvolatile memory1520 are coupled to a bus 1522 that is also coupled to random accessmemory (“RAM”) 1524, a processing portion (which includes N processingcomponents) 1526, an optional field programmable gate array (FPGA) 1527,and a transceiver component 1528 that includes N transceivers. Althoughthe components depicted in FIG. 15 represent physical components, FIG.15 is not intended to be a detailed hardware diagram; thus many of thecomponents depicted in FIG. 15 may be realized by common constructs ordistributed among additional physical components. Moreover, it iscontemplated that other existing and yet-to-be developed physicalcomponents and architectures may be utilized to implement the functionalcomponents described with reference to FIG. 15.

This display portion 1512 generally operates to provide a user interfacefor a user, and in several implementations, the display is realized by atouchscreen display. In general, the nonvolatile memory 720 isnon-transitory memory that functions to store (e.g., persistently store)data and processor-executable code (including executable code that isassociated with effectuating the methods described herein). In someembodiments for example, the nonvolatile memory 1520 includes bootloadercode, operating system code, file system code, and non-transitoryprocessor-executable code to facilitate the execution of the methodsdescribed herein (e.g., the methods described with reference to of FIGS.11, 13, and 14).

In many implementations, the nonvolatile memory 1520 is realized byflash memory (e.g., NAND or ONENAND memory), but it is contemplated thatother memory types may also be utilized. Although it may be possible toexecute the code from the nonvolatile memory 1520, the executable codein the nonvolatile memory is typically loaded into RAM 1524 and executedby one or more of the N processing components in the processing portion1526.

The N processing components in connection with RAM 1524 generallyoperate to execute the instructions stored in nonvolatile memory 1520 toenable synchronization among equipment coupled to a plasma processingsystem. For example, non-transitory, processor-executable code toeffectuate methods of synchronously pulsing and changing voltages of thesource generators and bias supplies may be persistently stored innonvolatile memory 1520 and executed by the N processing components inconnection with RAM 1524. As one of ordinarily skill in the art willappreciate, the processing portion 726 may include a video processor,digital signal processor (DSP), micro-controller, graphics processingunit (GPU), or other hardware processing components or combinations ofhardware and software processing components (e.g., an FPGA or an FPGAincluding digital logic processing portions).

In addition, or in the alternative, the processing portion 1526 may beconfigured to effectuate one or more aspects of the methodologiesdescribed herein (e.g., methods of synchronously operating equipment ofa plasma processing equipment). For example, non-transitoryprocessor-readable instructions may be stored in the nonvolatile memory1520 or in RAM 1524 and when executed on the processing portion 1526,cause the processing portion 1526 to perform methods of synchronouslyoperating modulating supplies and other equipment. Alternatively,non-transitory FPGA-configuration-instructions may be persistentlystored in nonvolatile memory 1520 and accessed by the processing portion1526 (e.g., during boot up) to configure the hardware-configurableportions of the processing portion 1526 to effectuate the functionsdisclosed herein (including the functions of the synchronizationcontroller 1016.

The input component 1530 operates to receive signals (e.g., thesynchronization signals or datasets with waveform characterization data)that are indicative of one or more aspects of the synchronized controlbetween equipment of a plasma processing system. The signals received atthe input component may include, for example, the power control and datasignals, or control signals from a user interface. The output componentgenerally operates to provide one or more analog or digital signals toeffectuate an operational aspect of the synchronization between theequipment. For example, the output portion 1532 may out thesynchronization signal and/or waveform datasets.

The depicted transceiver component 1528 includes N transceiver chains,which may be used for communicating with external devices via wirelessor wireline networks. Each of the N transceiver chains may represent atransceiver associated with a particular communication scheme (e.g.,WiFi, Ethernet, Profibus, etc.).

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present invention may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present invention may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

As used herein, the recitation of “at least one of A, B or C” isintended to mean “either A, B, C or any combination of A, B and C.” Theprevious description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the present disclosure.Various modifications to these embodiments will be readily apparent tothose skilled in the art, and the generic principles defined herein maybe applied to other embodiments without departing from the spirit orscope of the disclosure. Thus, the present disclosure is not intended tobe limited to the embodiments shown herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A plasma processing system, comprising: a plasmachamber including one or more bias electrodes; a bias supply coupled toat least one of the bias electrodes; a waveform-characterization moduleconfigured to generate a waveform dataset for an output waveform of thebias supply, the waveform dataset characterizes the output waveformduring a repetition period, T, of the output waveform; and awaveform-communication module configured to communicate the waveformdata set to another piece of equipment connected to the plasma system.2. The plasma processing system of claim 1, including a synchronizationmodule configured to send a synchronization pulse with asynchronization-pulse-repetition-period that is an integer multiple of Tto the other piece of equipment connected to the plasma system.
 3. Theplasma processing system of claim 1, wherein thewaveform-characterization module is configured to generate the waveformdataset as a collection of time-output-value pairs to represent theoutput waveform of the bias supply during the repetition period, T. 4.The plasma processing system of claim 3, wherein each of thetime-output-value pairs includes a time value and at least one of avoltage value, current value, or power value to represent the outputwaveform of the bias supply during the repetition period, T.
 5. Theplasma processing system of claim 3 wherein thewaveform-characterization module is configured to generate a pluralityof waveform datasets, each of the plurality of waveform datasetscharacterizes a corresponding one of a plurality of output waveforms,and each of the output waveforms is output from a corresponding one of aplurality of pieces of equipment connected to the plasma chamber;wherein the waveform-repetition module is configured to determine afundamental-repetition period, Tf, that is a shortest length of time forwhich all of the plurality of output waveforms are periodic with periodTf; wherein the waveform communication module is configured tocommunicate each of the waveform data sets for each of the plurality ofpieces of equipment to one or more of other of pieces of equipmentconnected to the plasma system; and wherein the synchronization moduleis configured to send a synchronization pulse with a synchronizationpulse repetition period that is an integer multiple of Tf to one or moreof the plurality of pieces of equipment.
 6. The plasma processingcontrol system of claim 5, wherein the synchronization module isconfigured to send synchronization ticks between the synchronizationpulses if an oscillator of one of the pieces of equipment connected tothe plasma system is not accurate enough to maintain time withsufficient accuracy within the fundamental-repetition period, Tf.
 7. Theplasma processing control system of claim 6 wherein the synchronizationticks are distinguished from the synchronization pulses by using a pulsewith of a different duration from that of the synchronization pulse forthe synchronization tick.
 8. A plasma processing system comprising: aplasma chamber including one or more bias electrodes; a bias supplycoupled to at least one of the bias electrodes and configured to applyan output waveform having a repetition period, T; a synchronizationmodule configured to send a synchronization pulse with asynchronization-signal-repetition-period that is an integer multiple ofT to at least one other piece of equipment connected to the plasmasystem; and a waveform communication module configured to communicatecharacteristics of the output waveform generated by the bias supply tothe at least one other piece of equipment connected to the plasma systemto enable the at least one other piece of equipment connected to theplasma system to adjust its output.
 9. The plasma processing system ofclaim 8, wherein the waveform-communication module is configured tocommunicate the characteristics of the output waveform as a collectionof time-output-value pairs to represent the output waveform of the biassupply during the repetition period, T.
 10. A plasma processing methodcomprising: generating and sustaining a plasma in a plasma chamber;producing a surface potential on a surface of a workpiece in the plasmachamber by applying, with a bias supply, an output waveform to a biaselectrode within the plasma chamber, the output waveform having arepetition period, T; producing a waveform dataset to represent theoutput waveform of the bias supply during the repetition period, T;sending the waveform dataset to one or more other pieces of equipmentconnected to the plasma chamber; and sending a synchronization pulsewith a synchronization-pulse-repetition-period to the one or more otherpieces of equipment connected to the plasma chamber to enablesynchronization among the one or more other pieces of equipment.
 11. Themethod of claim 10, wherein the waveform dataset includestime-output-value pairs, each of the time-output-value pairs including atime value and at least one of a voltage value, current value, or powervalue to represent the output waveform of the bias supply during therepetition period, T.
 12. The method of claim 10, including: sending thesynchronization pulse with a synchronization-pulse-repetition-periodthat is an integer multiple of T to the one or more other pieces ofequipment connected to the plasma chamber.
 13. The method of claim 11including: generating a plurality of waveform datasets, each of theplurality of waveform datasets characterizes a corresponding one of aplurality of output waveforms, and each of the output waveforms isoutput from a corresponding one of the other pieces of equipmentconnected to the plasma chamber; determining a fundamental-repetitionperiod, Tf, that is a shortest length of time for which all of theplurality of output waveforms are periodic with period Tf; and sendingthe synchronization pulse with a synchronization pulse repetition periodthat is an integer multiple of Tf to at least one of the other pieces ofequipment connected to the plasma chamber.